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Pharmacokinetics is the study of how the body absorbs, distributes, and eventually eliminates pharmacological compounds. In other words, what does the body do with the drug? This area includes the manner in which the drug is administered.

An introduction to pharmacokinetic principles will help you understand why specific drugs are administered in certain ways. Why, for example, can some drugs be administered orally while others need to be administered by injection, inhalation, or other non-oral routes? Likewise, drugs must reach a specific organ or “target” tissue to exert therapeutic effects, and various pharmacokinetic variables must be taken into account to maximize the drug's ability to reach these tissues. Finally, it is critical to know how the body metabolizes and eliminates a drug so that you can be aware of problems that might arise if drug metabolism is altered by illness, disease, or other factors. This chapter will begin by considering various routes of administration. Other pharmacokinetic issues, such as drug absorption, distribution, and storage, will then be addressed. Drug metabolism will be covered in the next chapter.


In general, drugs can be administered via two primary routes: the alimentary canal (enteral administration) or the nonalimentary routes (parenteral administration). Each route has several variations, and each offers distinct advantages and disadvantages. The key features of various routes are discussed here (see Table 2-1). For a more detailed description of the specific methodology involved in drug administration, the references at the end of this chapter include several excellent resources on this topic.13




The most common ...

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